JPH0251947B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating composition for dip coating containing a chlorinated hydrocarbon as a main component, which is particularly stable for a long period of time in a chlorinated hydrocarbon solvent, and is easily crosslinked by baking drying after coating. The object of the present invention is to provide a thermosetting composition for dipping coating that has a three-dimensional network structure and provides excellent coating performance. Dip coating is a process in which the object to be coated is immersed in a coating composition containing chlorinated hydrocarbon as the main solvent while being heated, and the coating composition is passed through a vapor layer of chlorinated hydrocarbon formed on top of the coating. It is already widely implemented. This coating method uses non-flammable or flame-retardant solvents, so there is no risk of fire, and since the coated object and vapor layer are heated, it dries quickly and prevents dripping, accumulation, dirt, and dust from sticking. There should be no coating defects such as, etc., and a smooth and uniform coating film should be obtained due to the leveling effect while passing through the vapor layer, and the solvent vapor should be free from organic solvents used in other dip coatings and water vapor. And because it has a higher specific gravity than air,
The solvent vapor that evaporates from the coating tank and the surface of the object to be coated is easily and automatically collected into the paint tank by a simple cooling recovery operation, which has the advantage of reducing solvent loss compared to other dip coating methods. , is an industrially very useful coating method, but on the other hand, the conditions required for the paint are very strict. That is, since the paint is used in a heated state, both the resin component and the chlorinated hydrocarbon solvent are required to be stable over a long period of time, and chemical reactions such as decomposition and crosslinking of each component may occur. There must be no inconveniences such as thickening, agglomeration, separation and sedimentation, discoloration, etc. For this reason, coating compositions for hot dip coating using chlorinated hydrocarbons as solvents should have thermoplastic resin components. Resins have been widely used. In recent years, however, there has been an increasing demand for more durable coatings, and in response to this demand, the applicant has developed coatings that are stable for long periods of time in heated chlorinated hydrocarbon solvents and that can be easily baked and dried. A thermosetting coating composition that crosslinks to form a durable coating film was previously proposed (Japanese Patent Publication No. 45176/1983 and Japanese Patent Publication No. 49/9082). Furthermore, recently, energy saving and resource saving during painting have become important issues, and countermeasures have become urgently needed. In this regard, resource conservation has already been carried out by forcibly collecting and reusing the evaporated solvent from the coating tank and the surface of the object to be coated, for example by enclosing the upper part of the coating tank. On the other hand, in order to save energy, there is a need for lower baking temperatures and shorter baking times for paints.
In general, the reduction in baking temperature depends on the amount and combination of crosslinking components.
This is possible depending on the selection of the cross-linking agent, but on the other hand, the stability of the paint may decrease, and in terms of physical properties, the paint film becomes hard and brittle, and the adhesion is particularly poor due to repeated cold and heat cycles. Adhesion is reduced under certain conditions. The present inventors have made extensive studies to solve the problems described above, such as the stability of the paint, the physical properties of the paint film, and the decrease in the adhesion of the paint film. By blending a plasto resin and an epoxy resin and limiting the composition of the solvent, these problems were solved and the present invention was completed. That is, the present invention provides 5 to 30% by weight of an N-methylol compound of an α,β ethylenically unsaturated carboxylic acid amide or an alkoxymethyl derivative and a polymerizable monomer having a hydroxyl group and )
Consists of a copolymer of 0.5 to 5% by weight of α,β-ethylenically unsaturated carboxylic acid and (C) 94.5 to 65% by weight of a copolymerizable vinyl monomer other than (A) and (B) above. Resin content [] (functional group-containing vinyl resin) 45-88% by weight and aminoplast resin (resin content []) 10-40%
Weight% and epoxy resin (resin content []) 2 to 15
% by weight, a chlorinated hydrocarbon solvent (solvent []) of 80% by weight or more and a lower aliphatic alcohol solvent (solvent []) of 20% by weight or less, and the lower aliphatic alcohol is the resin component. component
This is a dip coating composition comprising 15 parts by weight or more of a solvent component per 100 parts by weight. The composition of the composition of the present invention will be explained in order below. Among the monomers constituting the resin [], first a monomer having a hydroxyl group and an N-methylol compound of α,β-ethylenically unsaturated carboxylic acid amide or an alkoxy As a methyl derivative (monomer A),
Hydroxymethyl acrylate, hydroxymethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,
2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, ethylene glycol monoacrylate, ethylene glycol monomethacrylate, propylene glycol monoacrylate, propylene glycol monomethacrylate, polyethylene glycol monoacrylate, polyethylene Hydroxyl group-containing monomers such as glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, 3-chloro-2-hydroxypropyl methacrylate, hydroxymethyl diacetone acrylamide, acrylamide, methacrylamide, itaconic acid amide, crotonic acid amide N-methylol compounds of α,β-unsaturated carboxylic acids, which are adducts of formaldehyde, etc., and methanol, ethanol, propanol,
An alkoxymethyl derivative etherified with butanol or the like is used. These monomers A are functional monomers necessary for crosslinking with the aminoplast resin (resin component [ ]) used in combination, forming a three-dimensional network structure in the coating film, and increasing the durability of the coating film. in,
It is required to account for 5 to 30% by weight in the copolymer. If it is less than 5% by weight, the crosslinking density between the copolymer and the aminoplast resin will be low and a coating film with practical durability will not be formed, whereas if it is more than 30% by weight, the crosslinking density will be too high. This is not suitable because it not only makes the coating film brittle but also reduces the stability of the coating material. The proportion of these monomers A in the copolymer is particularly preferably 10 to 25% by weight. Examples of the α,β-ethylenically unsaturated carboxylic acid (monomer B), which is the second essential component forming the resin component, include acrylic acid, methacrylic acid,
These include maleic acid (maleic anhydride), itaconic acid, crotonic acid, etc., and their copolymerization ratio should be 0.5 to 5% by weight. This monomer B itself acts as a crosslinking component that reacts with the hydroxyl group, methylol group, or alkoxymethyl group in the resin component [], aminoplast resin (resin component []), and epoxy resin (resin component []). At the same time, it has a catalytic effect that promotes the crosslinking reaction during baking drying, and is a component that contributes to lowering the baking temperature.If the proportion is less than 0.5% by weight, the catalytic effect will not be fully exerted. If the amount is more than 5% by weight, the stability of the paint itself will drop sharply, and at the same time, the adhesion of the paint film due to heating and cooling cycles will become poor, both of which will lack practicality. The desirable proportion of the monomer B in the copolymer is 0.5 to 3% by weight. The other vinyl monomer (monomer C) copolymerized with the monomer A and monomer B is a component forming the main skeleton of the resin component [], and includes acrylic acid,
Or esters such as methyl ester, ethyl ester, propyl ester, butyl ester, hexyl ester, cyclohexyl ester, octyl ester, and decyl ester of methacrylic acid,
styrene, vinyltoluene, acrylonitrile,
Non-functional monomers such as methacrylonitrile, vinyl acetate, and vinyl propionate may be used alone or in combination depending on the purpose. Particularly preferred monomers from the viewpoint of durability are acrylic esters and methacrylic esters, and styrene, vinyltoluene, acrylonitrile, vinyl acetate, etc. are preferably used in small amounts, if at all. These monomers C are 94.5~
It needs to be 65% by weight, and if it is outside this range, the copolymerization ratio of monomer A and monomer B will be excessive or insufficient, resulting in inconvenience. The preferred copolymerization ratio of monomer C is 89.5 to 72% by weight. The resin component [] that constitutes the present invention is an aminoplast resin, which is a component that crosslinks with the functional group in the resin component [], and both commercially available melamine resins and benzoguanamine resins for paints can be used. I can do it. In particular, when the purpose is low-temperature crosslinking at 180°C or lower, it is preferable that each triazine ring has at least one methylol group or imino group, with the remainder being alkoxymethyl groups. One example is Mitsui Toatsu Chemical Co., Ltd.
manufactured by Yuban 20SE, 22R, 60, 61, 62, 220, Melan 22, 28 manufactured by Hitachi Chemical Co., Ltd., Super Betsucomin G-821-60 manufactured by Dainippon Ink and Chemicals Co., Ltd., Sanwa Co., Ltd. Chemical Nikaratsuk MS-21, Sumitomo Chemical
These include Sumimaru M-50S manufactured by Co., Ltd. and Vansemin 125-60 manufactured by Harima Kasei Co., Ltd. The resin component [ ], which is another component of the composition of the present invention, is an epoxy resin, and any commercially available epoxy resin can be used, but bisphenol A type epoxy resin is particularly preferred. Epicoat 801 manufactured by Ciel Epoxy Co., Ltd.
807, 808, 815, 816, 819, 1001, 1002, 1003,
1004, 1007, 1009, OL-53, OL-55, Araldite GY-257, 252, 255, manufactured by Nippon Ciba Geigy Co., Ltd.
250, 260, 280, 6071, 7071, 7072, 6084, 7097,
6097, 6099, 820, 985E, Dainippon Ink Chemical Industry
Epicron 800, 840, 850, 855, 857, 860, manufactured by Co., Ltd.
There are 1050, 4050, 7050, 9050, etc. Epoxy resins other than those mentioned above include DRH-151, 1, 151, 2, and 151.3 manufactured by Ciel Chemical Co., Ltd.
Chitsonox CX-221, 289, manufactured by Chitso Corporation.
Cycloaliphatic epoxy resins such as 206, 1222, 301, and 313, or aliphatic epoxy resins such as Denacol EX-800 series, 900 series, and 200 series manufactured by Nagase Sangyo Co., Ltd., can also be used. The blending proportions of these resin components [], [], and [] are required to be 45 to 88% by weight, 10 to 40% by weight, and 2 to 15% by weight. . If the resin content [ ] is less than 10% by weight, crosslinking will not be sufficient and a strong coating film will not be formed, and if it is more than 40% by weight, the crosslinking density will be too high and the coating film will be brittle and its adhesion will decrease. The stability of the paint also deteriorates. The resin content [] has the function of imparting flexibility to the paint film and improving adhesion and chemical resistance.If it is less than 2% by weight, its functions will not be fully expressed, and if it is more than 15% by weight, the paint will deteriorate. Stability deteriorates. Particularly, bisphenol type epoxy resin is a resin suitably used as the resin component [] in the present invention, but if its amount is too large, it tends to reduce only the weather resistance. The preferred blending ratios of each resin component are: resin component [] 60 to 80% by weight, resin component [] 15 to 30% by weight,
Resin content [] is 5 to 10% by weight. Next, the solvent component in the composition of the present invention will be explained. The main component of the solvent is a chlorinated hydrocarbon solvent (solvent [ ]), and in order to make the paint nonflammable or flame retardant, the solvent is added to the surface of the paint by taking advantage of the fact that the vapor density is higher than that of air. By forming a vapor layer and passing the object to be coated through the vapor layer, the coating film is given uniformity and quick-drying properties, and furthermore, in order to improve the automatic recovery efficiency of the solvent and further reduce solvent loss. In order to sufficiently repel these effects, the chlorinated hydrocarbon solvent must account for 80% by weight or more of the total solvent components. Examples of chlorinated hydrocarbon solvents that can be blended in the present invention include trichlorethylene, methylene chloride, 1,
1,1-trichloroethane, perchlorethylene, carbon tetrachloride, chloroform, 1,2-dichloroethylene, 1,1,2-trichloropropane,
1,2,3-trichloropropane, 1,1,2-
Examples include trichloroethane, and particularly preferred are those with a boiling point.
Those that are not flammable at 30°C to 130°C are used alone or in combination. The solvent [ ] is a lower aliphatic alcohol solvent or a solvent other than a chlorinated hydrocarbon solvent, and its proportion must be 20% by weight or less of the total solvent components. If the amount is higher than this, the blending ratio of the chlorinated hydrocarbon solvent will decrease relatively.
The above effects cannot be fully expected. The lower aliphatic alcohol solvent in the solvent [] is an essential component to maintain the long-term stability of the paint, and is 15 parts by weight based on the total of 100 parts by weight of the resin components [], [], and []. It is necessary to make it more than part by weight. Preferred lower aliphatic alcohol solvents include methanol, ethanol, n-propanol, isopropanol, and n-propanol.
butanol, isobutanol, sec-butanol,
These include tert-butanol, amyl alcohol, hexyl alcohol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, and the like. In addition, solvents other than halogenated hydrocarbons and lower aliphatic alcohols, such as toluene and other aromatic hydrocarbon solvents, ester solvents such as ethyl acetate, ketone solvents such as acetone, and others are used as resin dissolution aids or to adjust the viscosity. It is also possible to use them together as desired within a range that satisfies the composition ratio of the above-mentioned essential solvents. The desirable quantitative range of the solvent in the composition of the present invention is that the solvent [] is 85% by weight or more and the solvent [] is 15% by weight or less, and the amount of the lower aliphatic alcohol solvent in the solvent [] is the resin component. The amount is preferably 20 parts by weight or more per 100 parts by weight. It is also useful to incorporate various inorganic or organic colorants (pigments, dyes), extender pigments, matting agents, etc. into the composition of the present invention, and also various stabilizers,
It is also useful to include antifoaming agents, leveling agents, dispersants, and other commonly used paint additives. There is no particular restriction on the ratio of the resin component to the solvent component in the composition of the present invention, but the concentration of the resin component in the composition is generally 5 to 40% by weight, and pigments, fillers, and other additives are further blended. For compositions, the total solids concentration is 5 to 50.
Weight % is normal. The resin content (total solid content) concentration at the time of use is appropriately determined depending on the required thickness of the coating film, etc. Describing one example of the method for preparing the composition of the present invention, first, the resin component [] can be produced by ordinary solution polymerization. That is, common organic solvents such as alcohols such as methanol, ethanol, propanol, butanol, aromatic hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, or methyl cellosolve and ethyl cellosolve. , a cellosolve solvent such as butyl cellosolve, a ketone solvent such as acetone, methyl ethyl ketone, or a chlorinated hydrocarbon solvent as described above, by mixing the required monomers A, B, and C in a predetermined ratio. , using a radical polymerization initiator such as azobisisobutyronitrile, benzoyl peroxide, etc.
Polymerize at 100℃. The monomer mixture is added continuously or batchwise. The most preferred polymerization method is to copolymerize using a lower aliphatic alcohol solvent, which is an essential component of the entire composition of the present invention, as a polymerization solvent in an amount of 15% by weight or more based on the resin content. It is desirable to make the solids concentration of the polymer solution as high as possible, and this can be achieved by polymerizing at a high solids concentration (high monomer concentration) or by evaporating the solvent after polymerization. This increases the degree of freedom in mixing solvents during composition preparation, making it easier to formulate a desired solvent composition. Next, predetermined amounts of aminoplast resin, epoxy resin, chlorinated hydrocarbon solvent, and lower aliphatic alcohol solvent are blended into the copolymer solution obtained in this way, and other solvents are blended as necessary. , a composition of the invention is prepared. The dip coating composition according to the present invention can be used for dip coating various metal and nonmetal products. The temperature of the paint during painting is within the range of room temperature to the boiling point of the chlorinated hydrocarbon solvent that is the main solvent, and is determined as appropriate depending on the stability of the paint and the finish (uniformity, quick drying, etc.) of the paint. Especially when a uniform finish is desired, the vapor pressure of the chlorinated hydrocarbon solvent is
A temperature of 150 mmHg or higher is preferred. As a coating method, it is possible to adopt a method that is already known or has been put into practical use for paints using chlorinated hydrocarbon solvents, and after dipping the object under the above conditions. Preferably, after the object to be coated has reached the same temperature as the coating material, uniform coating is achieved by drawing the vapor layer of the chlorinated hydrocarbon solvent formed on the surface of the coating liquid at a constant speed. The pulling speed of the object to be coated is usually 0.5 to 2.5 m/min. The coated object is heated to 30℃ at 120 to 250℃.
By baking and drying for 10 minutes to 10 minutes, the coating film is sufficiently crosslinked into a three-dimensional network structure. The composition according to the present invention is stable over a long period of time and is suitable for dip coating at room temperature or under heating.
Forms a cross-linked coating film with a three-dimensional network structure even at fairly low baking temperatures, and the performance of the coating film is excellent and well-balanced in terms of hardness, solvent resistance, adhesion, chemical resistance, and other aspects. Moreover, it exhibits an outstanding feature in terms of adhesion during cooling and heating cycles. For example, by using a paint obtained by removing the epoxy resin from an example of the composition of the present invention, that is, a paint containing a functional group-containing acrylic resin and a low-temperature crosslinking melamine resin,
When painting anodized aluminum alloy materials, baking at 150°C for 30 minutes will
Although the coating film is presumed to be sufficiently crosslinked based on its hardness, solvent resistance, etc., one cycle is defined as holding the object to be coated in boiling water for 8 hours and then at -20℃ for 16 hours. When subjected to a heat-cool cycle test, phenomena such as peeling of the coating film and light selective fall are observed after 1 to 5 cycles. On the other hand, if the composition of the present invention containing an epoxy resin, that is, a paint containing functional group-containing acrylic resin, low-temperature crosslinking melamine, and epoxy resin as resin components, was applied and baked in the same manner as above. There were no abnormalities in the 5-cycle heat-cool cycle test, and it can withstand even harsher usage conditions. These features mean that even if the composition of the composition or the material of the object to be coated changes,
The same is found in the compositions of the present invention. In addition, if the material to be coated is a material that inherently has good corrosion resistance, such as aluminum, it is not so noticeable, but
When targeting iron or other easily corrosive materials, it is noticeable that the composition of the present invention forms a highly anticorrosive coating film. EXAMPLES The present invention will be explained in more detail by showing Examples and Comparative Examples below. The objects to be coated, test methods, etc. in each of the following examples are as follows, and the composition of each example and each test result are collectively shown in Table 1 at the end. Anodized aluminum: Aluminum is anodized according to a conventional method to form an oxide film of a predetermined thickness at a temperature of 80 to
The samples were washed with hot water at 100°C for 5 to 10 minutes and then dried. Test method: Paint film appearance; according to JIS-A-4706. Pencil hardness: Same as above Adhesion: JIS-A-4706 adhesion test and Dupont impact test (1/2φ, 500g
50cm) overall judgment. Alkali resistance; according to JIS-A-4706. the time is
72 hours. Solvent resistance: Rub the painted surface 100 times with gauze impregnated with methyl ethyl ketone to determine the extent of scratches. Heat/cool cycle adhesion; boiling water (96°C or higher) 8
One cycle was 16 hours at -20°C, and this was repeated 7 times, and the condition of the painted surface was visually judged. Weather resistance: Based on Sunshine Weather-Ometer. After 500 hours of irradiation, measure the photoselectivity retention rate (60° reflectance). Judgment criteria for test results: Coating film performance; 〇...No abnormality, △...Slight abnormality, ×...Major abnormality Composition stability: 〇...Almost unchanged, △...
Slightly thickened, ×... Significantly thickened or gelled Abbreviations: IBM; Isobutyl acrylate MMA; Methyl methacrylate St; Styrene AA; Acrylic acid HEA; β-Hydroxyethyl acrylate AIBN; Azobisisobutyronitrile BA; Butyl Acrylate MAA; methacrylic acid HEMA; β-hydroxyethyl methacrylate CHA; cyclohexyl acrylate ITA; itaconic acid 2EHA; 2-ethylhexyl acrylate N-MAM; N-methylolacrylamide EMA; ethyl methacrylate Product name description: Yuban; Mitsui Toatsu Chemical ( Melamine resin manufactured by Nikaratsuku; Melamine resin manufactured by Sanwa Chemical Co., Ltd. Sumimaru; Melamine resin manufactured by Sumitomo Chemical Co., Ltd. Epicoat; Epoxy resin manufactured by Yuka Ciel Epoxy Co., Ltd. DER-732; Epoxy resin DRH151 manufactured by Dow Chemical Co., Ltd. .2; Epoxy resin manufactured by Ciel Chemical Co., Ltd. Epicron; Epoxy resin manufactured by Dainippon Ink and Chemicals Co., Ltd. Trichlorene Penter; Trichlorethylene for paints manufactured by Toagosei Chemical Co., Ltd. Anti-aging DAH; manufactured by Kawaguchi Chemical Co., Ltd. Agents Antige DBH; anti-aging agent manufactured by Kawaguchi Chemical Co., Ltd. Slamylizer TPS; anti-aging agent manufactured by Sumitomo Chemical Co., Ltd. Taipeiku CR-90; white pigment (titanium oxide) manufactured by Ishihara Sangyo Co., Ltd. Example 1 and comparative examples 1. Pour 756 g of isopropanol into 3 flasks equipped with a reflux condenser, thermometer, and stirrer, and heat to 80℃.
Keep at ±2℃ IBA490g, MMA560g, St126g,
A mixture of monomers consisting of 14 g of AA and 210 g of HEA and 28 g of AIBN as a polymerization initiator was continuously added dropwise over 6 hours, and stirring was continued for 2 hours at the same temperature to carry out polymerization. Subsequently, under heating and reduced pressure,
378g of isopropanol, the polymerization solvent, was distilled out,
Next, 1022 g of methylene chloride was added to obtain a resin solution with a resin content of 50% (referred to as resin solution A). A clear paint (resin content: 30%) having the following composition was prepared using this resin liquid.

[Table] Pour this clear paint into a round coating tank of approximately 2000ml, keep it at 35℃, and dip-coat a 70 x 150mm anodized aluminum plate (oxide film thickness 9μ) at a pulling speed of 1.7m/mm. , baked and dried at 150°C for 30 minutes. The coating performance was as shown in Table 1, and the Example composition of the present invention was superior to the Comparative Example composition. Further, the stability of the composition was sufficiently maintained. Example 2 and Comparative Examples 2 and 3 In the same manner as in Example 1, 756 g of n-butanol
BA406g, MMA560g, St140g, MAA42 inside
A mixture of g, 252 g of HEMA, and 35 g of AIBN was continuously added dropwise at 90°C for 6 hours, and after continued heating and stirring for an additional 2 hours, 406 g of n-butanol was distilled off under reduced pressure. In addition, a resin solution with a resin content of 50% was obtained (referred to as resin solution B). A clear paint with the following composition (resin content is 20% in each case) was prepared using this resin liquid.

[Table] Example 3 and Comparative Example 4 In the same manner as in Example 1, isopropanol 756
In g, CHA322g, MMA420g, ITA28g,
A mixture of 350 g of HEMA and 28 g of AIBN was continuously added dropwise at 80° C. over 5 hours, and heating and stirring were continued for an additional 1.5 hours to complete the polymerization reaction. Subsequently, 350 g of isopropanol was distilled out under reduced pressure, and then 1050 g of carbon tetrachloride was added to obtain a resin solution with a resin content of 50% (referred to as resin liquid C). Using this resin liquid, a clear paint with the following composition ( The resin content was 25% in each case.

【table】

[Table] Example 4 In the same manner as in Example 1, isopropanol 378
g, 2EHA392 in a mixed solvent of 378 g of methanol.
g, MMA700g, St112g, AA56g, N-
A mixture of 140 g of MAM and 28 g of AIBN was continuously added dropwise at 70° C. for 6 hours, and the reaction was continued for an additional 2 hours to complete the polymerization. After distilling off 378g of the mixed solvent under reduced pressure, 1022g of methylene chloride was added to remove the resin.
A 50% resin solution was obtained (resin solution D). A clear paint (resin content: 28%) with the following composition was prepared using this resin liquid.

[Table] Example 5 In the same manner as in Example 1, 756 g of isobutanol
Inside, IBA476g, EMA280g, MMA350g,
14g of MAA, 280g of HEA, 28g of AIBN at 90℃
After continuous dropwise addition over a period of time, the reaction was continued for an additional 2 hours to complete the reaction. followed by isobutanol
After 378 g was distilled off, 1022 g of trichlorethylene penta was added to obtain a resin solution with a resin content of 50% (resin solution E).
Using this resin liquid, a white paint having the following composition (resin content: 19%, solid content: 38%) was prepared.

【table】

[Table] Comparative Examples 5 to 10 Resin liquids F, G, H, I, J, K (resin content is 50%
%) was polymerized and prepared. As the solvent, a mixed solvent of 378 g of methanol and 378 g of isopropanol was used, and 28 g of AIBN was used.

[Table] Using these resin solutions F to K, mix 150 g of Yuban 220 as a melamine resin, 22.5 g of Epicoat 1001 as an epoxy resin, and 65.2 g of methylene chloride to 675 g of each resin solution to create a clear paint with a resin content of 30%. I mixed it. Comparative Examples 5 to 9 (resin liquids F to J)
In the case of Euban using n-butanol as a solvent,
220 was used as is, but Comparative Example 10 (resin liquid K)
Melamine resin in Yuban 220 solvent n-
Butanol was replaced with xylol. Using this clear paint, a 70 x 150 mm size anodized aluminum plate (anodized film thickness 9 μm) was dip coated at 30°C in the same manner as in Example 1, at a pulling speed of 1.5 m/mm, and then heated to 160°C. Baked dry for 30 minutes. The coating film performance and stability were as shown in Table 1, and were inferior to the composition of the present invention.

【table】

[Table] ** When the material to be coated is anodized aluminum plate.

Claims (1)

[Claims] 1 Consists of a resin component and its solvent component, where the resin component has the following resin content [] 45 to 88% by weight, resin content [] 10 to 40% by weight, and resin content [] 2 to 15% by weight. %, and the solvent component consists of the following solvent [] 80% by weight or more and solvent [] 20% by weight or less, and the amount of lower aliphatic alcohol solvent in the solvent [] is based on 100 parts by weight of the resin component. A dip coating composition containing 15 parts by weight or more. Resin component [ ]: A copolymer consisting of the following monomers (A), (B) and (C). (A) 5 to 30% by weight of a functional monomer selected from N-methylol compounds or alkoxymethyl derivatives of α,β-ethylenically unsaturated carboxylic acid amides and polymerizable monomers having hydroxyl groups. (B) α,β-ethylenically unsaturated carboxylic acid 0.5~
5% by weight. (C) 94.5 to 65% by weight of copolymerizable vinyl monomers other than (A) and (B) above. Resin component []: Aminoplast resin. Resin component []: Epoxy resin. Solvent [ ]: Chlorinated hydrocarbon solvent. Solvent [ ]: A solvent other than the above solvent [ ] consisting of a lower aliphatic alcohol solvent.